Electronic switch



Aug. 5, 1958 E. l... HAVENS.

ELECTRONIC SWITCH 2 Sheets-Shea?s l Filed Sept. 29. 1954 'A7' TORNE Y E.L. HAE/ENS ELECTRONIC SWlTC'H Aug. 5 195s ATTORNEY nited States Patent Cmnemonic swrrcn Byron L. Havens, Closter, N. J., assignor toInternational Business Machines Corporation, New York, N. Y., acorporation of New York Application September 29, 1954, Serial No.459,111

7 Claims. (Cl. Z50-27) The present invention relates to an electronicswitch and more particularly to what is known in the art as amulti-channel electronic switch.

Briefly, the novel electronic switch herein disclosed is capable oftransmitting in serial order, a plurality of distinct sources ofinformation. Further, the switch includes means for selecting any one ofsaid plurality of sources and transmitting only the selected one.

The novel electronic switch herein disclosed in conjunction with anordinary oscilloscope, also nds application in many electronic circuitsincluding those ultilized in computers and complex switching networks.

The primary object of the present invention is an improved multi-channelelectronic switch.

A second object of the present invention is an improved electronicswitch for use in simultaneously displaying on the screen of a cathoderay tube, a plurality of items of information.

A yet additional object of the present invention is a multi-channelelectronic switch that is fast, accurate and reliable in operation,simple and economical to produce, and not subject to transientdisturbances.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated of applying that principle.

In the drawings:

Fig. l is a block diagram disclosing how the two sheets of drawingcontaining Figs. 2 and 3, respectively, are to be joined;

Fig. 2 is a portion of Fig. l of the complete disclosure of themulti-channel switch;

Fig. 3 is the second portion of Fig. l of the complete disclosure of themulti-channel switch;

Fig. 4 discloses a plurality of voltage waveforms that will be explainedin conjunction with the electronic switch of Figs. 2 and 3; and

Fig. 5 discloses a schematic drawing of the face of the cathode ray tubeshowing in particular the relative displacement ofthe channels when thenovel electronic switch herein disclosed is utilized in conjunction withan oscilloscope.

By denition, the term up used hereinafter will indicate a voltage pulseor shift in voltage in the positive direction, Whereas the term downwill indicate a voltage pulse or shift in voltage in the negativedirection. The terms up and down will be used without regard to theoriginal and final voltage values. In brief, throughout the terms up anddown are relative and not absolute.

Reference is made to Fig. 2, of composite Fig. 1, and in particular tothe circuitry enclosed by the broken line labelled Source of VoltageWaveforms. The circuitry enclosed within this broken line consists of asine wave generator S whose output is coupled through a capacitor C1 tothe control grid of an inverter tube TV1. The plate of inverter tube TV1is coupled through capacitor C2 to a 2,846,575'. Patented Aug. 5, 1958first trigger that includes tubes TA and TB. The plate of tube TB of thefirst trigger is coupled through capacitor C3 to a second trigger thatincludes tubes TC and TD.

Briey, the first and second triggers are binary connected and respond toa source of negative pulses obtained from the plate of inverter tubeIV1. In the illustrative embodiment herein disclosed, the sign wavegenerator S will have a period of approximately sixteen microseconds (afrequency of approximately 16 cycles per second).

Thus the sine wave generator will result, through the medium of inverterTV1 in a negative pulse being impressed on the input of the firsttrigger circuit every sixteen microseconds. Correspondingly, the outputof said first trigger circuit (being binary coupled to said secondtrigger circuit) will result in a negative pulse being impressed on theinput of said second trigger circuit every thirty-two microseconds. Thusthe tirst trigger circuit will change its condition every sixteenmicroseconds, whereas the second trigger circuit will change itscondition every thirty-two microseconds. Hence, the waveforms at theanode of tube TA will be generally of the type shown by the waveform Aof Fig. 4. Correspondingly, the anodes of tubes TB, TC, and TD willrespectively have appearing thereat waveforms of the generalconfiguration of waveforms B, C and D of Fig. 4. That is, the anode oftube TA will be up during the first sixteen-microsecond period, downduring the second sixteen-microsecond period and continue in thisfashion. The anode of tube TD will at al1 times be in the oppositecondition (up or down) to that of the anode of tube TA. The anode oftube TC will be up during the rst two consecutive sixteen-microsecondperiods, and down during the next two consecutive sixteen-microsecondperiods and continue in this manner. The anode of tube TD will at alltimes be in the opposite condition (up or down) to that of the anode oftube TC.

Now still referring to Fig. 2, it will be seen that there are fourcathode follower tubes (CF1 through CFA) having their plates connectedin common to a positive source of potential of approximately volts inmagnitude and their cathodes respectively connected, each through aseparate resistor, to a negative source of potential of approximately110 volts. The cathode follower tubes CF1- CF4 are represented aspentodes having their screen and suppressor grids connected to suitablepotentials and their respective control grids connected to the plates oftubes TA, TB, Tc and TD of the tirst and second triggers of the sourceof voltage waveforms.

The control grid of cathode follower CF1 is connected to the anode oftube TA and thus the potential at the cathode of tube CF1 will begenerally of the form represented by waveform A of Fig. 4.Correspondingly the potential at the cathodes of cathode followers CP2,CF3 and CFA will be respectively generally of the form represented bywaveforms B, C and D of Fig. 4.

Now still referring to Fig. 3 and in particular to twin diodes 17, 18,27, 28, 29 and 30, it will be seen that: the anodes of twin diode 27 areconnected in common through lead 10 to the cathode of cathode followerCF1; that the anodes of twin diode 28 are connected in common throughlead 11 to the cathode of cathode follower CF2; that the anodes of twindiode 29 are connected in common through lead 12 to the cathode ofcathode follower CFS; and that the anodes of twin diode 30 are connectedin common through lead 13 to the cathode of cathode follower CFA. Fromthe preceding discussion of the cathode followers, it will now beapparent that the anodes of twin diodes 27 through 30, respectively,have impressed thereon voltage waveforms generally of the formrepresented by waveforms A through D shown in Fig. 4. Still referring toFig. 3 and in particular to twin diodes 17 and 18 and their immediatelyassociated circuitry. For purposes of explanation, it will be convenientto refer to the right diode of twin diode 18 as diode ISR and the leftdiode of twin diode 18 as diode 18L, and correspondingly as to twindiode 17. The anode of diode 17R and the cathode of diode 18L areconnected in common by lead 31 and serially through current limitingresistor 1S and lead 11 to the cathode of cathode follower CF2. Theanode of diode 17L and the cathode of diode 18R are connected in commonby lead 32, and serially through current limiting resistor 16 and lead13 to the cathode of cathode follower CF1. Serially connected betweenleads 31 and 32 is a pair of resistors R and R1. The mid-point of theseries circuit consisting of resistors R5 and R1 has a lead 36 connectedthereto. Resistor R5 is approximately twice the size of resistor R1 inohmic magnitude. Resistors R5 and R1 in conjunction with currentlimiting resistors 15 and 16 may be thought of as a current resistoradding network. These four resistors are enclosed by a broken linelabelled Current Resistor Adding Network, and are eiective inconjunction with the additional circuitry, hereinafter more fullyexplained, in impressing on lead 36 a waveform generally of the form ofthat represented by waveform E of Fig. 4.

Still referring to Figs. 3, it will be seen that the cathodes of diodes17L and 17R are connected in common and through lead 33 to a tap, onresistor R1 and through capacitor C1 to ground. The anodes of diodes 18Land 18R are connected in common through lead 34 to a tap on resistor R2,and through capacitor C5 to ground. It will be seen that resistors R1,R2 and R3 are serially connected between ground and a potential sourceof approximately negative 180 volts magnitude. Thus resistors R1, R2 andR5 constitute a potentiometer arrangement for effectively impressing andsubstantially maintaining a rst potential V2 on lead 33 and a secondpotential V1 on lead 34. The relative magnitudes of potentials V1 and V2are shown by waveform E of Fig. 4.

Waveform E of Fig. 4 during the rst sixteen-microsecond period or timeinterval has a magnitude of approximately V1. During the secondsixteen-microsecond period Waveform E has a magnitude of approximatelyDuring the third sixteen-microsecond period waveform E has a magnitudeof approximately During the last sixteen-microsecond period waveform Ehas a magnitude of V2. Thus it is seen that waveform E is essentially astep wave having four uniform steps.

The waveform E of Fig. 4 is developed in the following manner: diode 17Rserves to prevent lead 31 from becoming more positive than the potentialV2; diode 17L serves to prevent lead 32 from becoming more positive thanthe potential V2; diode 18L serves to prevent lead 31 from becoming morenegative than potential V1; and diode 18R serves to prevent lead 32 frombecoming more negative than potential V1. Thus it is apparent that thepotential on lead 31 and lead 32, respectively, may only vary from V1 toV2.

It will be recalled that waveform E is the potential appearing at themid-point of resistors R5 and R1 which are serially connected betweenleads 31 and 32 (R5 being approximately twice as large as R1). Thepotential appearng at the mid-point, namely, waveform E, will heutilized as explained hereinafter to determine the relative verticalposition of the cathode ray tube beam during the four successivesixteen-microsecond time intervals.

Now referring to Fig. 4, waveforms B and D in particular, it will beseen that during the first time interval leads 11 and 13 arerespectively in the down condition. Under these conditions there will beno potential difference between leads 11 and 13 and the potential at themidpoint of serially connected resistors R5 and R1 will be approximatelyV1; that is, the step of lowest magnitude occurring during the rst timeinterval of waveform E of Fig. 4.

During the second time interval, that is, the second sixteen-microsecondperiod shown in Fig. 4, a waveform B is up and waveform D is down Thisresults in a potential difference between leads 11 and 13 resulting in aflow of current from lead 11 through resistors 15, R5 and R1 to lead 13.Now it will be recalled as pointed out earlier, that R5 is approximatelytwice as large in ohmic value as resistor R1', hence the potentialdropped across resistor R5 as a result of the current flowing from lead11 to lead 13, is approximately two-thirds of the potential existingbetween leads 11 and 13. Viewed in another manner, the potential on lead13 is lower than the potential on lead 11 and the potential at themid-point of resistors R5 and R1 is approximately one-third of thepotential difference between said leads. Thus it is seen that during thesecond time interval or sixteen-microsecond period, the magnitude ofvoltage waveform E of Fig. 4 is approximately During the thirdsixteen-microsecond period lead 11 is down while lead 13 is up. Theseconditions will be apparent from an inspection of waveforms B and D ofFig. 4. Hence current will flow from lead 13 through resistors 16, R1,R5 and 16 to lead 11. The potential dropped across resistors R1 and R5will be in the ratio of l to 2, the same ratio as during the secondsixteen-microsecond period, supra. However, it is to be appreciated thatduring the third time interval, the polarity of the potential isreversed since during the second time interval lead 11 was up and lead13 down, whereas during the instant time interval (third) the conditionsare exactly reverse. Hence, it will be apparent that during the thirdtime interval lead 36 which manifests waveform E will have a potentialimpressed upon it of a magnitude of approximately Referring to Fig. 4,it will be seen that during the fourth time interval, leads 11 and 13are each in the up condition. Thus there will be no potential differencebetween leads 11 and 13 and no current will ilow through resistors R5and R1 as a result of a potential difference between leads 11 and 13.Actually viewing the situation in another manner leads 31 and 32 may bethought of as being respectively at approximately a potential ofmagnitude V2. Thus the junction point of resistors R5 and R1 connectedbetween leads 31 and 32 will be at a potential of approximately V2.

Waveform E shown in Fig. 4 and developed in the manner explained above,is applied via lead 36 to the input of a sweep amplifier. Referring toFig. 3 and enclosed within a broken line labelled Sweep Amplier is acircuit that may be used. Essentially the sweep amplifier `shown in Fig.3 consists of an inverter circuit including inverter tube IVG coupledthrough a capacitor C7 to an amplier circuit including amplifier tubeA1. (It is to be noted that the plate of tube A1 is connected throughlead 71, resistor R70 and lead 72 to the cathode of tube IV5.)

Brieily, the sweep ampliiier of Fig. 3 functions in the followingmanner: The voltage waveform generally of the type represented bywaveform E of Fig. 4 is impressed via lead 36 and capacitor C5 on thecontrol grid of inverter tube IVG. The plate of inverter tube IVS iscoupled via capacitor C7 to the control grid of amplifier tube A1. ltwill now be apparent from an inspection of the circuitry of the sweepamplifier of Fig. 3, that when the potential on the control grid ofinverter tube IVG goes up the potential on the control grid of amplifiertube A1 goes down and the potential at the plate of amplifier tube A1goes up. In actuality then the sweep amplifier may be thought of asmerely amplifier means since when the input, i. e., lead of the sweepamplifier, is up, the output of the sweep amplifier, i. e., plate oftube A1, is "up. Thus when a voltage waveform of the type represented bywaveform E of Fig. 4 is impressed on lead 36, a voltage waveformgenerally of the type represented by waveform 1VP shown in Fig. 4 willbe available at the plate of tube A1.

Now still referring to Fig. 3 it will be seen that voltage waveform lVPappearing at the plate of tube A1 is impressed via lead 61 on verticaldeflection plate 1V of the cathode ray tube CRT. As is apparent to thoseskilled in the art, the potentials impressed on deflection plates 1V and2V of cathode ray tube CRT will determine the vertical displacement ofthe beam.

Referring to Figs. 2 and 3 it will be seen: that the anodes of twindiode 27 are connected to the cathode ot' cathode follower CF1; that theanodes of twin diode 23 are connected to the cathode of cathode followerCF2; that the anodes of twin diodes 29 are connected to the cathode ofcathode follower CFB; and that the anodes of twin diode 30 are connectedto the cathode of cathode follower CF4. Now for convenience, the leftdiode of twin diode 27 will be referred to as diode 27L and the rightdiode of twin diode 27 as diode 27R. Corresponding notation will beutilized with respect to twin diodes 28, 29 and 30. It will be observed:that the cathodes of diodes 27R and 29R are respectively connectedthrough lead 83, resistor 87 and lead 82 to a source of negativepotential of approximately ll() `volts in magni tude; that the cathodesof diodes 28R and 29L are respectively connected through lead.84,resistor 88 and lead Si to a source of negative potential ofapproximately ll() volts in magnitude; that the cathodes of diodes 27Land 30R are respectively connected through lead 85, resistor 89 and leadS2 to a source of negative potential of approximately ll() volts inmagnitude; and that the cathodes of diodes ZSL and 30L are respectivelyconnected through lead 86, resistor 90, and lead 82 to a source ofnegative potential of approximately llO volts in magnitude. In otherwords, each of the above-mentioned pair of diodes and the assothenegative llO volt source circuit which is most freart as a logical diodeOR ciated resistor connected to comprise a diode mixing quently referredto in the circuit.

It will now be appreciated that during the first time interval (waveformA and C of Fig. 4) leads 10 and l2 which are respectively connected tothe cathodes of cathode follower tubes CF1 and CFE, will be in the upcondition. Thus the potential impressed on the anodes of twin diodes 27and 29 will be such as to render the following diodes conductive,namely, 271., 27R, 2.9L and 29R. When the afore-recited diodes areconductive, then leads 83, 84 and S5 will be respectively in the upcondition and lead '86 will be in the down condition. (Leads 83, S4 and85 will be in the up condition as a result of the potential droppedacross resistors 87, 88 and 89.) The aforo-recited conditions occurduring the first sixteen-microsecond period or time interval asrepresented in Fig. 4.

Referring to Fig. 3, it will be seen that there are four invertercircuits each having an inverter tube respectively labelled iV2, iV3,IV4 and lV5. Each of the four inverter circuits is substantiallyidentical and each has a potential of approximately llO volts impressedthrough a resistor on the plate of the inverter tube and the cathodeconnected to a potential of approximately negative ll0 volts. Invertertubes IV2 through IV5 are pentodes. Each of the screen grids of the fourpentode tubes are respectively connected through a resistor to lead 35.Lead 35 is also connected to the 0 position of switch S1, the screengrid of tube A1 of the sweep amplifier, and through a resistor 35A to asource of negative potential of approximately 180 volts in magnitude.(It will be noted that when switch S2 is in the 0 position, lead 35 iseffectively at ground potential as the movable contact of said switch isgrounded through lead 81.)

Now assuming that switch Sl is the 0 position, then the screen grids ofeach of the four inverter circuits IV2 through TV5 will be atapproximately ground potential. Now observing from Fig. 3 that thecontrol grid of tube IV2 is connected through a resistor to ground andthrough a capacitor C7 to lead 83, it Will be appreciated that duringthe rst time interval (sixteenmicrosecond period) since lead 83 is inthe up condition the control grid of tube IV2 will be up rendering saidtube conductive. Tubes IVB and IV., will be respectively conductiveduring the first time interval as a result of leads 84 and 85 beingrespectively in the up condition. The circuitry in the case of tubesTV3, IV4 and IVE, and leads 84, 85 and 86, respectively, corresponds tothat explained in detail with respect to tube IV2.

Thus it will be apparent that during the first sixteenmicrosecond periodinverter tubes IV2, IV?, and IV are respectively conductive and theanodes of each of said tubes will be in a down condition, whereasinverter tube IV5 will be non-conductive and the anode of said tube willbe in an up condition.

The cathodes of twin diodes 39 and 40 are respectively connected eachthrough a separate resistor to the plates of inverter tubes IV2 throughIV5. In detail, the circuitry is as follows: the cathode of diode 39R isconnected through resistor R11, to the plate of tube IV2; the cathode ofdiode 39L is connected through resistor R11 to the plate of tube IV3;the cathode of diode 40R is connected through resistor R12 to the plateof tube IV4; and the cathode of diode 40L is connected through resistorR13 to the plate of tube TV5. It will now be apparent that during thefirst time interval the plates of tubes IV2, TV3 and IV will berespectively in the down condition resulting in the cathodes of thefollowing diodes, namely, 39R, 3.9L and 40R, being respectively in thedown condition. Correspondingly, the plate of tube IV5 is up during thefirst time interval and thus the cathode of diode 40L wil be up duringsaid interval.

Now still referring to Fig. 3, there are four identical cathode followercircuits respectively including cathode follower tubes OF5 through CFB.The cathode follower tubes are pentodes each having their plateconnected through a separate resistor to a potential of approximatelypositive llO volts in magnitude. The cathodes of cathode follower tubesCF5 through CFS are connected in common by lead 50 and through resistorR6 (resistor R6 is a common cathode resistor) to a source of potentialof approximately negative Volts. Lead 50 is also connected to the 0position of switch S2. The control grids of cathode follower tubes CF5through CFS are respectively connected as follows: the control grid oftube CF5 is connected through lead 62 to the anode of diode 39L andthrough resistor R14 to lead 52; the control grid of tube CFG isconnected through lead 61 to the anode of diode 39R and through resistorR15 to lead 51; the control grid of tube CF', is connected through lead54 to the anode of diode 40L and through resistor R16 to lead 54; andthe control grid of' tube CF1, is connected through lead 53 to the anodeof diode 40R and through resistor R11 to lead 53. Leads 51 through 55shown in the upper portion of Fig. 3 also respectively interconnectinput terminals 1 through 5 with switch positions l through 5 of switchS2.

Input terminals 1 through 5 will normally have impressed thereon voltagewaveforms that it is desired to View on the face of the CRT tube of theoscilloscope. Consider for the present only input terminals 1 through 4and assume that both switches S1 and S2 are in their respectivepositions. Now recalling that4 during the first time interval thecathodes of diodes 39L, 39R and 4DR are respectively down, whereas thecathode of diode 40L is up, it will be appreciated that if leads 51, 52and 53 respectively were to attempt to manifest a positive potentialthat diodes 39L, 39R and 40R would become conductive. In brief, duringthe first time interval diodes 39L, 39R and 40R serve to clamp thecontrol grids of cathode followers OF5, OF5 and CFB thus precluding anyinformation in the form of voltage waveforms appearing on inputterminals 1, 2 or 3, respectively, from being transmitted by theafore-recited cathode follower tubes. However, since the cathode ofdiode 40L is up during the first time interval, lead 54 may go positiveas a result of an input voltage being impressed on input terminal 4.Since lead 54 is free to go positive during the rst time interval, thecontrol grid of cathode follower tube CF7 will follow the condition oflead 54 and the condition of lead 54 will, during the first timeinterval, be manifested on lead 50. In brief, the voltage waveformimpressed on input terminal 4 during the first time interval, will,during said interval be manifested by the potential on lead S0.

Now referring to Fig. 4, it will be observed that voltage waveforms Band C are up during the second sixteen-microsecond interval. Thus leads11 and 12 are respectively up and twin diodes 28 and 29 are eachconductive during said interval. When twin diodes 28 and 29 areconductive, then leads 83, 84 and 86 are respectively in the upcondition, whereas lead 85 will be in the down condition. When leads 83,84 and 86 are up, then inverter tubes IVZ, IV3 and 1V5 are respectivelyconductive. Since lead 85 is down inverter tube IV., is non-conductive.With inverter tube IV4 nonconductive, the cathode of diode 40R is up,whereas the cathodes of diodes 39L, 39R and 40L are respectively down.The anode of diode 40R is connected through lead 53 to the control gridof cathode follower CFS and said control grid is also connected throughresistor R17 to lead 53. Lead 53 is connected between input terminal 3and the 3 position of switch S2. It will now be apparent that sinceswitches S1 and S2 are each in their respective "0 positions, thatduring the second time interval the voltage waveform impressed on inputterminal 3 will, through the medium of cathode follower tube CFB andresistor Re, appear on lead 50.

Once again referring to Fig. 4, it will be observed that during thethird sixteen-microsecond period, waveforms A and D are respectively upWhen waveforms A and D are up the following conditions exist: leads 10and 13 are respectively up, twin diodes 27 and 30 are each conductive;leads 83, 85 and 86 are respectively up, whereas lead 84 is down,inverter tubes IVZ, IV4 and IV5 are respectively conductive, whereasinverter tube IV3 is non-conductive; and the cathode of diode 39L is up,whereas the cathodes of diodes 39R, 40L and 4612 are downf From thepreceding discussion with respect to the first and second time intervalsand the afore-recited conditions that occur during the third timeinterval, it will be apparent that the voltage waveform impressed oninput terminal 2 (through lead 52, resistorv R14 and the control grid ofcathode follower CF5) will be manifested by the up-down condition oflead 50 during the third sixteen-microsecond period.

Still referring to Fig. 4, it will be observed that during the fourthsiXteen-microsecond period waveforms B and D are up and the followingconditions exist: leads 11 and 13 respectively in the up condition; twindiodes 28 and 30 are each conductive; leads 84, 85 and 86 arerespectively up, whereas lead 83 is down; inverter tubes IV3, IV4, andIV5 are respectively conductive, whereas tube W2 is non-conductive; andthe cathode of diode 39R is up, whereas the cathodes of diodes 39L, 40Land 40K are each down.

It will be apparent that during the fourth time interval during whichthe cathode of diode 39R is up, that the voltage waveform impressed oninput terminal 1 will be manifested on lead 50 as a result of thefollowing circuitry: lead 51, resistor R15, cathode follower tube GF6and common cathode resistor R5.

To briefly summarize: with switches S1 and S2 in their respective Opositions, the information appearing in the form of voltage waveforms oninput terminals 1 through 4 will be respectively manifested during thefirst through fourth sixteen-microsecond time intervals of Fig. 4. Thevoltage waveform 1VP of Fig. 4 will be impressed during the first fourtime intervals on vertical deflection plate 1V of cathode ray tube CRT.

Now referring to Fig. 3, it will be seen that lead 50 is connected tothe 0 position terminal of switch S2 and that when said switch is in its0 position, the voltage manifested on lead 50 will, through lead 82, beimpressed on the control grid of cathode follower tube CFS. Cathodefollower tube CFQ and amplifier tube AZ comprise twin triode 100. Twintriode and its associated circuitry is enclosed within a broken linelabelled Non- Inverting Amplifier. The non-inverting amplier accepts itsinput from lead 82 and manifests its output on lead 92. Briey, thenon-inverting amplifier consists of a cathode follower coupled to agrounded grid amplifier. The output of the non-inverting amplifierappearing on lead 92 is impressed on the control grid of cathodefollower CFm. The output of cathode follower CFm is impressed via lead62 on vertical deection plate 2V of cathode ray tube CRT. Thus it isapparent that the information appearing on lead 50 is, through themedium of the non-inverting amplifier and cathode follower CFM),impressed on the second vertical deflection plate of the cathode raytube. The first vertical deflection plate 1V has impressed thereonvoltage waveform 1VP.

In Fig. 3 a horizontal sweep circuit is represented by a block havingits output impressed on horizontal deliection plates 1H and 2H of thecathode ray tube CRT. The potential impressed on horizontal plate 1H isgenerally of the type shown in waveform 1HP of Fig. 4 and the potentialimpressed on horizontal deiiection plate 2H is generally of the typeshown in waveform ZHP of Fig. 4. Circuits for developing the waveformslHP and 2HP are well known in the art and thus no detailed discussion ofany such circuit is deemed necessary herein.

It will now be apparent that the information in the forrn of voltagewaveforms impressed on input terminals 1, 2, 3 and 4 will respectivelyappear displaced on the face of cathode ray tube CRT generally inaccordance with the showing of Fig. 5, that is, the information frominput terminal 4 will be mainfested by a visual indication varying upand down in the vicinity of channel 4 shown as a straight line in Fig.5. Correspondingly, the information impressed upon input terminals 1, 2and 3 will be mainfested respectively in the general vicinity ofchannels 1, 2 and 3 of Fig. 5.

Throughout the preceding discussion switches S2 and S1 were each intheir respective 0 position. Now assume that it is desired to exhibit onthe face of cathode ray tube CRT only one of the four inputsrespectively impressed on input terminals 1, 2, 3 and 4 or an inputimpressed on input terminal 5. Assume, for purpose of explanation, thatit is desired to only view the waveform impressed on input terminal 3,then it is necessary to transfer switches S1 and S2 each to their 3position.

With switches S1 and S2 respectively in their 3 position, the followingconditions exist: lead 35 is no longer grounded but is at a highlynegative potential of approximately negative volts. (This conditionresults from switch S1 being transferred from its "0 position.) Withlead 35 highly negative, the screen grids of inverter tubes IV2 throughIV5 and amplifier tube A1 will be highly negative. This will result ininverter tubes IV2 through IV being precluded from being renderedconductive. Also the sweep amplifier including amplifier tube A1 will beineffective, i. e., a constant output manifested on lead 61. Since noneof the inverter circuits IV2 through IV 5 can be rendered conductive, noorderly selection of the waveforms impressed on input terminals 1, 2, 3and 4 will appear on lead 50. However, under the conditions assumed atthis time, switch S2 is in its positon 3 and hence lead 50 is notconnected to the input of the noninverting amplifier. Input terminal 3however, is connected through lead 53, switch S2, to the input, namely,lead 82, of the non-inverting amplifier. Thus the output of thenon-inverting amplifier, namely lead 92, will manifest the waveformimpressed on input terminal 3 and will be impressed via cathode followertube CF1@ and lead 62 on vertical deiiection plate 1V of cathode raytube CRT.

It will now be apparent that manifested on the face of the oscilloscopewill be the waveform impressed on terminal 3. It will also be apparentto those skilled in the art that suitable variations in the frequency ofthe horizontal sweep circuit may be made when a single waveform is to beexhibited by the oscilloscope.

Correspondingly, when switches S1 and S2 are each in their first throughfifth positions, the waveforms impressed on input terminals 1, 2, 3, 4and 5 will respectively be exhibited on the face of the oscilloscope.Again under certain circumstances it may be desirable to adjust thefrequency of the horizontal sweep circuit.

It will be apparent that when switches S1 and S2 are respectively intheir 0 position resulting in the information impressed on inputterminals 1 through 4 being simultaneously exhibited by theoscilloscope, that the waveforms appearing at said input terminals mustbe of the proper frequency. The period of the waveforms impressed uponinput terminals 1 through 4 under the condition of the illustrativeembodiment must be either sixteen microseconds or properly relatedthereto. It is to be appreciated, however, that the invention disclosedis not limited to a device employing a sixteen-microsecond period butthat by judicious design a wide Variation is available.

Further, although the circuits for the non-inverting amplifier and thesweep amplifier are shown in detail, any of a number of circuits wellknown in the art may be utilized in place of said circuits. voltagewaveforms shown in Fig. 2 is merely illustrative of one suitable sourceof the desired waveforms.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims.

What is claimed is:

l. A multi-channel electronic switch capable of cyclically assuming anumber of conductive conditions, said switch being controlled by aplurality of voltage waveforms and including: a plurality of cathodefollower circuit means responsive to said plurality of voltagewaveforms; a plurality of inverter circuit means; a plurality of diodemixing circuit means, each coupling a plurality of said cathode followermeans to a predetermined one of said inverter circuit means; a pluralityof second cathode follower means each comprising a channel of saidswitch; a plurality of input terminals respectively coupled to saidsecond cathode follower means; clamping diode means respectivelycoupling each said second cath- Also the source of r ode follower meansto a predetermined one of said inverter circuit means for conditioningsaid second cathode follower means to transmit an input signal; andmeans combining the outputs of all of said second cathode follower meansinto a single output channel, whereby signals respectively impressed onsaid input terminals are cyclically transmitted to said single outputchannel.

2. A multi-channel electronic switch as claimed in claim l furthercharacterized by the provision of current adder means controlled by saidrst cathode follower means for rendering a repetitive step voltagewaveform.

3. A multi-channel electronic switch as claimed in claim 1 furthercharacterized in that means is provided for selecting and transmitting apredetermined one of said plurality of inputs impressed on saidplurality of input terminals of said multi-channel switch.

4. A multi-channel electronic switch adapted for producing a voltagewaveform having a plurality of steps and for rendering operative one ofa plurality of paths during each step of said voltage waveforms, saidswitch including a plurality of input terminals, a plurality of cathodefollowers respectively associated with said plurality of inputterminals, means for combining the outputs of said plurality of cathodefollowers into a single channel for application to an oscilloscope,first means for controlling said plurality of cathode followers wherebyonly one of said cathode followers is conductive at any one time andthat said cathode followers are each conductive in cyclic order therebytransmitting the electrical input impressed on the input terminalassociated with said cathode follower, current adding means comprising apair of serially connected resistors and including means for maintainingthe variation in potential of each of the extremities of said seriallyconnected resistors between a lower voltage limit and an upper voltagelimit, means coupling a first extremity of said serially connectedresistors to said first means and responsive thereto to cause current toow through said resistors in a first direction, and further meanscoupling the other extremity of said resistors to said first means andresponsive thereto to cause current to flow through said resistors inthe opposite direction, and amplifier means connected to the juncture ofsaid serially connected resistors to amplify the voltage waveformpresent thereat having the general configuration of a step wave, eachstep in said voltage waveform corresponding and occurring at the timeduring which only a particular cathode follower is conductive.

5. A multi-channel electronic switch as claimed in claim 4 furthercharacterized in that the means for generating a voltage waveform havingthe general configuration of a step wave includes: a plurality ofcathode follower means, a current adding network controlled bypredetermined ones of said cathode follower means and adapted to producea step wave voltage, and amplifying means coupled to said current addingnetwork for amplifying said step wave voltage.

6. An electronic circuit adapted to produce a voltage waveform havingthe general configuration of a step wave, said electronic circuitincluding a first source of rectangular voltage pulses each pulse offixed duration, a second source of voltage pulses synchronized with saidfirst source for producing rectangular voltage pulses of twice the`duration of the rectangular pulses of said first source, a first lead,a second lead, means for maintaining the variation in potential of saidfirst and second leads between a lower voltage limit and an uppervoltage limit, a first and second resistor serially connected betweensaid leads, means coupling said first lead to said first source to causecurrent to fiow through said first and second resistors in a firstdirection when the potential of said first source is greater than saidupper voltage limit and the potential of said second source is belowsaid lower voltage limit, means coupling said second lead to said secondsource to cause current to fiow through said first and second resistorsin the opposite direction when the potential of said rst source is lowerthan said lower voltage limit and the potential of said second source isabove said upper voltage limit whereby a step wave voltage isperiodically manifested at the junction between said resistors, andmeans coupling the junction of said resistors only to an amplier foramplifying said step wave voltage.

7. In an electronic circuit adapted to produce a step Wave voltage, afirst diode, a second diode, a third diode and a fourth diode, eachdiode having an anode and a cathode, a first source of fixed potentialimpressed on the cathodes of said first and second diodes, a secondsource of fixed potential impressed on the anodes of said second andfourth diodes, means connecting the anode of said first diode to thecathode of said third diode, means connecting the anode of said seconddiode to the cathode of said fourth diode, current adding meansconnected between the anode of said rst diode and the cathode of saidfourth diode, variable voltage means connected to the anode of saidfirst diode to cause current to ow through said current adding means ina first direction, and further variable volta-ge means connected to thecathode of said fourth diode to cause current to flow through saidcurrent adding means in the opposite direction whereby the output ofsaid current adding means is a voltage Waveform having the generalconfiguration of a step wave produced in response to the variations ofsaid variable voltage means and said 10 further variable voltage means.

References Cited in the le of this patent UNITED STATES PATENTS 152,413,440 Farrington Dec. 3l, 1946 2,474,266 Lyons June 28, 19492,668,188 Naslund Feb. 2, 1954 2,719,670 Jacobs et al. Oct. 4, 1955

